90 Mr. W. D. Lang—Revision of the 
5. P. [Porina] gastropora (Marsson), 1887, Pal. Abh. 
vol. iv. Heft 1, p. 86, pl. vill. fig. 11 ; mucronatus-zone ; 
Rugen. 
IV. PotycEPHALOPORA, gen. Nov. 
Genotype. P. hydra. 
Tabular Diagnoses of the Species. 
A. Apertures generally surrounded by three avi- 
cularia only, two proximal-lateral and one 
distal-lateral” Skee ce arta cee eter 1. P. trigemina. 
B. Apertures generally surrounded with four 
avicularia. 
I, Incrusting, unilaminar; eecia shorter, about 
once-and-a-half as long as broad. 
a. Less secondary intercecial tissue........ 2. P. rustica. 
b. More secondary intercecial tissue ...... 3. P. hydra, 
II. Incrusting, unilaminar ; cecia longer, about 
twice:as tony as WNGAd, 26 cieslosteeies oe nes 4, P. plicatella. 
III. Incrusting, multilaminar; cecia about 
once-and-a-half as long as broad. 
a Costes less hantoOred) circ t stetetckets steerer 5. P. multiplex. 
b. Coste more than’ 20). Sa es 6. P. insignis. 
C. Apertures generally surrounded with five 
avicularia. 
I. Incrusting or erect, unilaminar. 
a. Less coarse, 2 mm. long, or less; apertural 
bar very swollen ...... APSR a aetih he ss ade oP. duroida: 
b. Coarser. 
1. A fair amount of secondary intercecial 
TASS O apes stage = che (oan ete tect ine eee 8. P. multiceps. 
2. Little or no secondary intercecial tissue. 9. P. bulbifera. 
IL. Birect(bilamingr 5305 42)1s fates asp tele ets 10. P. pentapora, 
Membraniporella obscurata, Brydone (1916, Geol. Mag. 
dec. vi. vol. ii. p. 99, pl. vi. figs. 9, 10), from the cortestudi- 
narium-zone of S. England is possibly a Polycephalopora, 
but the figure and description are not clear enough to 
certify this. 
1. P. trigemina, sp. un. 
Type-specimen. British Museum, D. 29003 ; quadratus- 
zone ; depressus-subzone ; E. of Brighton, Sussex. 
2. P. | Semiescharipora] rustica (d’Orbigny), Pal. Frane. 
1852, pl. 718. figs. 13-16, 1853, p. 484; Senonian ; 
Sainte-Colombe, France. 
3. P. hydra, sp. n. 
Type-specimen. British Museum, D. 18001 ; mucronatus- 
zone; Riigen. 
